Nobody expects the Elemental Inquisiton.
I’ve browsed the forums for guides using the Arcanor sword but the ones that I’ve found are either very outdated or more on the Fire side of things. I’ve known from further reading that fully-Elemental builds are pretty tricky to do, but I tried building around it anyway. As I was finishing the Forgotten Gods main quest line with another character, this dropped for me:
I’ve searched the forums again for builds around this helm, but very few appear. This seems to support Elemental builds, so I combined Arcanor with the Horns of Korvaak and came up with this build.
Grimtools Link: updated stats, no item and skill changes
Grimtools Link (current build): changed pants, rings, and weapon component, updated stats and skills
STATS
updated for current build: permanent buffs on and standing in Seal, damage is for Forcewave
Damage breakdown for Forcewave
Gear
Weapon: Mythical Arcanor, Blade of the Luminari - core of the build
Head: Horns of Korvaak - +1 to Soldier and Inquisitor, has an Elemental RR proc that also Petrifies enemies. I’ve found that more enemies (except bosses) are susceptible to Petrify than Stun or Freeze, so this helps a ton when clearing mobs.
Amulet: Shambler’s Heart - +3 to Forcewave. The one in the Grimtools link is the best one I have so far to cover OA and resistances
Rings: Elemental Harmony Set - I chose this mainly for the OA and resistances, but the proc is also nice since the build is Elemental. Can be crafted for Slow Resistance
Current build: Mythical Signet of the Rune Father and Mythical Reign of Fire and Ice - 1st ring gives great overall bonuses, especially +2 to Inquisitor Seal. 2nd ring is Elemental Harmony set packed into one, but has less total OA and resistances. I crafted this one with Slow Resistance.
Chest: Mythical Shroud of Illusion - really good overall stats for a level 84 legendary, the toggle skill is a nice bonus.
Shoulders: Mythical Lifeblaze Mantle - one of the few non-set Elemental shoulders. Physical Resistance is good to have, Casting Speed helps Forcewave, and the proc is okay for the build.
Gloves: Mythical Inscribed Bracers - the legendary options are either set pieces or doesn’t fit the build, so I went with this.
Pants: Mythical Fateweaver’s Leggings - more OA, the proc helps a ton but is uncontrollable and has a long cooldown, so I don’t rely too much on it.
Current build: Aleksander’s Chausses - +3 to Rending Force and Steel Resolve. SR dropped me a useable one, you can see it in the 2nd GT link
Boots: Mythical Earthshatter Treads - I chose this to max out Forcewave. Petrify resist is also good.
Relic: Ignaffar’s Combustion - more Elemental RR, and I got the Aura of Censure completion bonus on the 2nd craft 
Belt: Mythical Scales of Beronath - +1 Inquisitor skills, +2 Inquisitor Seal, more OA
Medal: Mythical Sigil of the Bear King - probably the best medal for Forcewave builds, even though it has no Elemental Damage bonuses.
Skill Choices
I’ve tested various setups with skills, and the one in the Grimtools seems to be the most consistent for me.
Soldier
Forcewave (26/16), Rending Force (hardcap), Internal Trauma (1 point)
I’ve tried using maxed Internal Trauma since it is also converted (except Bleed) into Elemental, but the build already has a lot of procs and ambient damage so I just put it at 1 point.
Fighting Spirit (12/12)
The build has low base OA, and you will mostly be facetanking (on Seal, of course), so 12/12 for max benefits.
Blitz (1 point)
Just for movement.
Menhir’s Will (1 point)
The Soldier’s circuit breaker, but it mostly activates after Prismatic Diamond (50% health) and Ghoul (45%) health.
Field Command (hardcap), Squad Tactics (12/12)
Main skill is maxed for OA, modifier is 12/12 or even numbers after for the Casting Speed bonus
Military Conditioning (10/10)
More Defensive stuff, softcap is good enough.
Veterancy (1 point)
The bonuses doesn’t hurt to have, so only 1 point.
Decorated Soldier (1 point)
The build already has a ton of Elemental Resistance, but the Slow Resistance is the main thing here.
Scars of Battle (8/8)
Mainly for the Armor Absorption and CC Resistances
Inquisitor
Word of Renewal (13/12), Vigor (1 point), Steel Resolve (10/10), take Word of Arms transmuter
Your heal skill, also great buffs overall. Main skill is an odd number after 12 for the Movement Speed bonus.
Current build: 17/12, 6/10, 18/10
Word of Pain line (1 point each)
I bound Phoenix Fire here so I only use it when I want to trigger the devotion, mostly against bosses. The Impaired Aim debuff is a nice bonus, and it’s a bit of Elemental damage, as well.
Aura of Censure (20/12)
The +1 Aura of Censure from the Ignaffar’s Combustion relic is a must to get this to 20 points for the maximum Elemental RR possible with the build.
Storm Box of Elgoloth (16/16)
Since the build has low base OA, the DA shred from Storm Box helps a ton.
Current build: completely removed, reallocated to Word of Renewal and Inquisitor’s Seal
Inquisitor Seal (18/12), Arcane Empowerment (16/12)
The skill that lets you facetank. The Arcanor sword also gives -10% Elemental RR and more duration to this, so you and your enemy need to be inside the Seal for maximum effectiveness.
Current build: 21/12, 17/12
Deadly Aim (16/12)
Same as Fighting Spirit, this proc will boost your OA which you really need.
Devotions
Tier 1
Ghoul - up to proc only, no need to complete
Spider, Raven, Quill, Hawk - for affinity and mostly OA (Raven and Hawk)
Current build: Empty Throne (first node only) - some DA and Slow Resistance, point taken from Hyrian in the previous build
Tier 2
Kraken - default two-hand devotion, in my opinion
Rhowan’s Crown - Elemental RR proc, bound to Inquisitor Seal so it procs only when enemies are inside
Alladrah’s Phoenix - nodes have good stats, and I got the proc mostly for the flat Damage Absorption. This combined with Inquisitor’s Seal lets the build facetank most of the time. I bound it to Word of Pain and I only use it on bosses or a pack of Champion monsters in SR.
Harvestman’s Scythe and Bard’s Harp - Forcewave spam actually eats Energy really fast, combined with the Arcane Devastation from the sword and other skills. Bard’s Harp proc also gives us OA and Slow Resistance.
Hyrian, Guardian of the Celestial Gates - just the first node. I had an extra point, so why not.
Current build: I removed this point and placed it to the first node of Empty Throne for some DA and Slow Resistance
Tier 3
Blind Sage (up to proc only) - I originally got the Cold and Lightning nodes, as well, but I removed it to get Hawk for the OA. This is the first build that I made that used the Elemental Seekers proc, and it fits the build very well. This is bound to Forcewave so it takes advantage of the spam.
Performance
As you may have noticed by now, the build suffers from low OA and Physical Resistance as the playstyle sort of forces you and your enemy to be inside Inquisitor’s Seal for max damage. Otherwise, it’s fun to see all the procs while spamming Forcewave and Arcane Devastation.
Skeleton Key dungeon bosses: all facetanked without using Aether Clusters (you need to move away from Gargabol’s volcanoes, those really hurt when it’s directly under you)
Nemesis bosses: just be wary of things like Grava’thul’s Nullification missiles, Zantarin’s shotgun, Aleksander’s meteors, etc. Just reposition with Rune of Displacement and spam away.
Mad Queen: facetanked, less than 10 seconds. Prismatic Diamond procced, but that’s about it
Lokarr: facetanked, about 1-2 mins. Lokarr moved out of the Seals during this fight so I had to follow him
cleared SR 65-66 with Voidmarked mutator (-20% Casting Speed
) but with Armored (-10% Elemental RR to enemies ). SR 66 boss room was not fun with Aleksander, Moosi, Allostria, and Ilgorr trapping you
Celestials: I’ve tried to kill Mogdrogen, but I got him to 1/4 HP and my damage wasn’t keeping up, so I died 
for the others, well, no thanks.
Crucible: I don’t really play Crucible; it could work but struggle against tough boss waves.
Final Thoughts
I had struggled to put this build together since pure Elemental builds are usually worse than single Fire, Cold, or Lightning, but it was fun testing and figuring stuff out. This can definitely be improved; I might have missed out on other items since I just used what I have.